What is a Waterfall Word™? Join them; it only takes a minute: Sign up Error when passing undefined variable to function? Browse other questions tagged javascript firefox or ask your own question. As these examples demonstrate, the rules of type coercion can sometimes be clear as mud.

more stack exchange communities company blog Stack Exchange Inbox Reputation and Badges sign up log in tour help Tour Start here for a quick overview of the site Help Center Detailed asked 7 years ago viewed 7102 times active 7 years ago Blog Stack Overflow Podcast #91 - Can You Stump Nick Craver? The following example would throw a ReferenceError but it doesn't because TypeError gets there first. Why aren't there direct flights connecting Honolulu, Hawaii and London, UK?

For #6: IMHO, it is not a good practice to create closures for elements this way. Consider this example code snippet: Game.prototype.restart = function () { this.clearLocalStorage(); this.timer = setTimeout(function() { this.clearBoard(); // what is "this"? }, 0); }; Executing the above code results in the following A variable is undeclared when it does not use the var keyword. Its hard to inspect it in Firebug because if I put in a breakpoint I had to press continue all the times the call doesn't fail. –Tony Peterson May 28 '09

The Framework of a Riddle Compute the Eulerian number What happens to articles when dealing with abbrevations? C++ delete a pointer (free memory) Players Characters can't fill the fundamental requirements for a campaign Make an ASCII bat fly around an ASCII moon Should a router use SLAAC for properties in JavaScript Juriy Zaytsev ("kangax"): Understanding Delete Dmitry A. It's very slow compared to a simple cached for loop, as it constitutes a function call for each iteration which is pretty expensive.

A good example is the console. typeof foo JavaScript has quite a useful remedy for this: 1 typeoffoo;// "undefined" Unlike everything else in JavaScript, typeof will deal with whatever You hint at this problem with the msgValue variable but I think it's the main argument against passing a function body as a string. Linked 11 Passing undefined parameter to function - check if variable exists 5 angular.isDefined(obj) doesn't work if “obj” is undefined 2 Javascript modules, passing jQuery when it may not be loaded

How about trying to have people in the country who are awake at the time of interviews and calls before pretending to be a real company??????????????????????NorbertNo need for IIFE here, use So in theory at least you should be able to get away without ever using a typeof check against a ReferenceError Where can I read more? Hey! If you provide a name, use it, otherwise set the name to ‘default’; e.g.: var firstObj = new BaseObject(); var secondObj = new BaseObject('unique'); console.log(firstObj.name); // -> Results in 'default' console.log(secondObj.name);

So now we get: var thirdObj = new BaseObject('unique'); console.log(thirdObj.name); // -> Results in 'unique' delete thirdObj.name; console.log(thirdObj.name); // -> Results in 'default' Common Mistake #8: Creating incorrect references to instance In JavaScript there is Undefined (type), undefined (value) and undefined (variable). The fix for an undefined variable or function is easy, simply define it: var definedVariable = 'test';
typeof definedVariable; // "string"
function definedFunction(){
return "I'm defined!"
}
typeof definedFunction // "function" You can know if It would be useless processing for the JavaScript engine to also evaluate the second statement, because the end result will still be the same (false && true results in false, false

Related 4443JavaScript function declaration syntax: var fn = function() {} vs function fn() {}460How can I check whether a variable is defined in JavaScript?578How to check a not-defined variable in JavaScript253How Constant Length of \underline How to unlink (remove) the special hardlink "." created for a folder? Want to make things right, don't know with whom How do you grow in a skill when you're the company lead in that area? The issue here is more one of performance and efficiency.

Compilers don't have fragility (or egos!) of us human programers. I know how to contain these errors! javascript onclick share|improve this question asked Sep 25 '12 at 19:01 Lee 1,58352747 marked as duplicate by jbabey, Barmar, ЯegDwight, PeeHaa, tereško Sep 25 '12 at 22:55 This question has been Proof of that is this code, add it to the end of the code you were doing:

At this point any code that follows will not be executed. I do a test for undefined on a variable: if (x !== 'undefined'){} or even if (typeof x !== 'undefined'){} And the browser still throws an error: ReferenceError: x is not Specially the #1 and #2Mobile PunditsMost of the time when the project deadline is near and due to this In the hurry of development and releasing most of the people don't Join them; it only takes a minute: Sign up Script error : variable is undefined up vote 3 down vote favorite I have a javascript file that declares the variable below:

Without strict mode, assigning a value to an undeclared variable automatically creates a global variable with that name. more stack exchange communities company blog Stack Exchange Inbox Reputation and Badges sign up log in tour help Tour Start here for a quick overview of the site Help Center Detailed Here’s a TL;DR version I found quite useful when writing this. Disallows duplicate property names or parameter values.

Fill in your details below or click an icon to log in: Email (Address never made public) Name Website You are commenting using your WordPress.com account. (LogOut/Change) You are commenting using At first blush, JavaScript may seem quite simple. It makes me feel like I am almost in Haskel :p //partial application. Is there any way to get this function isDefined to work? //THIS WORKS AND RETURN FALSE alert(typeof sdfsdfsdfsdf !== 'undefined'); //THIS GIVES AN ERROR, WHY? //Uncaught ReferenceError: sdfsd is not defined

Adding a DOM element is an expensive operation. hopefully those points actually matter): 1 2 !!0;// false!!"0";// true This works because !foo converts foo to Where is shared and final layout in the security Editor Could winds of up to 150 km/h impact the structural loads on a Boeing 777? Please click the link in the confirmation email to activate your subscription.

I was using another method besides !r in one of the callers and that made the problem possible. –Tony Peterson May 28 '09 at 15:08 add a comment| up vote 2 If you declare it but leave it unassigned it is treated as undefined and won't through error, in your case it is not declared. If you give `null` as the first argument to `bind` then it won't set `this` for the function. In most other languages, the code above would lead to an error because the “life” (i.e., scope) of the variable i would be restricted to the for block.

asked 4 years ago viewed 1073 times active 4 years ago Blog Stack Overflow Podcast #91 - Can You Stump Nick Craver? If you wanted a language that would make for horrible code, difficult maintenance and ease of bug creation javascript has it all! Where the hell is toptal located????????????????????? share|improve this answer answered May 28 '09 at 15:02 Daniel Lew 54.7k23147157 Thanks for the comment.

TC39 seems to be in agreement on that most of the time. He boasts a proven competency in building cloud-scalable, extensible software and systems. How to avoid star-trails Extremely over tightened pinch bolt, how to remedy? share|improve this answer answered Sep 25 '12 at 19:08 Elmor 1,74642148 add a comment| up vote 0 down vote there is problem in your code.

These are the common mistakes novice programmers, like me, make. Reply bird says: October 5, 2012 at 01:38 "References which are neither properties or variables are by definition unresolvable and will throw a ReferenceError: foo; //ReferenceError JavaScript sees no explicit base Extremely over tightened pinch bolt, how to remedy? However, you also probably want to know how you're getting around it in the first place.

IdentifierName` (until that something to the left is no longer a MemberExpression; but Identifier ? `foo` ? in this case). Meh... Related 6569How do JavaScript closures work?3257How to remove a property from a JavaScript object?4443JavaScript function declaration syntax: var fn = function() {} vs function fn() {}1263What is the scope of variables Reply Karen Cox says: October 8, 2012 at 18:55 So what do I do if I get this message every time I try to type something. Finding none it ...

Why here? but this is all speculation without feedback from the op. The OP will have to post a comment as to why it may not be working with my answer. –Fred -ii- Aug 28 '14 at 15:43 @user574632 The OP's Because of this, example 3 will also return the same result: Example 3 function myFunction(a) { var power = 10; return a * power;} Try it Yourself » But, A very strange email Create new language version for content branch A Short Easy Addictive Riddle Want to make things...

What's the most confusing error you've seen? to Web Workers. In the following code, the variable x is not defined, and the if statement evaluates to true. Powered by W3.CSS. Looking forward Name:Email:Website:Wrap your code in